Field of the Invention
The invention relates to a plug-in electronic module and to a method for connecting a plug-in electronic module to a holding structure. It is used particularly for plug-in optoelectronic transceivers which are plugged into a housing arranged on a printed circuit board, in the course of which electrical contacts on an electronic circuit in the transceiver come into electrical contact with associated contacts on a connector arranged on the printed circuit board.
It is known practice to arrange optoelectronic transceivers on a printed circuit board such that they can be plugged in. In particular, plug-in “small form factor pluggable” (SFP) transceivers of small dimensions are known which are arranged in a housing on a printed circuit board.
A plug-in transceiver of small dimensions which is known in the prior art is shown in FIGS. 8a and 8b. Such a transceiver 100 normally has a housing 110 which contains, on a printed circuit board 140, electrical and optoelectronic components, particularly a transmission module such as a VCSEL laser and a reception module such as a photodiode, in a manner which is known per se. Light is injected and output between the optoelectronic transceiver 100 and an optical network via a plug holder 160 which is arranged in the region of one end of the housing 110.
To lock and unlock the transceiver in a housing into which the transceiver is plugged, a locking apparatus 120 is provided which can be in diverse forms and, by way of example, has a pivotable clip 121.
In addition, as FIGS. 8a and 8b show, resilient bulges 150 can be formed on the housing 110 which allow the transceiver to be mounted without play in an associated housing. In this case, provision can be made for the bulges 150 to be made of metal and to be connected to metal structures inside the transceiver, for example an internal shielding plate, so that the internal metal structures can be put at a particular electrical potential.
Formed on the underside of the printed circuit board 140 is a series of external electrical contacts 130 which are used for making contact with the electrical printed circuit board 140 or with the electrical and optoelectronic components arranged on the printed circuit board 140. These contacts 130 can be in the form of metal contact areas, but can likewise be in the form of electrical connection pins which are plugged into a connector.
The aforementioned aspects become clearer when consideration is also given to the housing or the holding apparatus into which the transceiver 100 can be plugged. Such a housing 30, which is preferably metal, is shown in FIG. 9. In the exemplary embodiment shown, the housing 30 comprises a top housing part 31 and a bottom housing part 32, but can also be of integral design in principle. The two housing parts 31, 32 are connected to one another when the housing 30 has been fully assembled. The interior of the housing 30 contains an electrical connector 20 which, like the housing 30, is arranged on an electrical printed circuit board 10. The electrical printed circuit board 10 is used to make the electrical contact for a multiplicity of electrical contacts 21 on the electrical connector 20.
When the transceiver 100 is plugged into the housing 30 along the arrow direction A-B, the electrical contacts 130 on the transceiver 100 come into contact with associated contacts 21 on the electrical connector 20, as a result of which the electrical and optoelectronic components arranged on the transceiver's printed circuit board 140 are electrically connected to the printed circuit board 10, so that radio-frequency information signals can be applied, for example.
The problem is now that the electrical contacts 130 on the transceiver or, generally, on an electronic module having electrical contacts need to be protected from electrostatic discharges which can occur when the transceiver is in the unplugged state, for example as a result of discharges of static electricity when touched by an operator who is handling the transceiver. Such static discharges can result in damage to and in failure of electronic circuits and parts of the transceiver.
In this context, it will be pointed out that the standard IEC 61000-4-2 makes particular provisions regarding protection of electronic parts from static discharges when two bodies having different electrostatic potentials move together and make direct contact.